Making sense of unsteady separation on a wing

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• Pascal Gehlert, University of Cambridge
• Friday 07 February 2020, 13:00-14:00
• LR5, CUED..

If you have a question about this talk, please contact Connor O'Pray.

Rapidly changing flow fields, for example caused by accelerating bodies such as flapping wings, can result in dramatically fluctuating force responses. Initially, added mass effects dominate. As time passes, vorticity created on the body surface, begins to shed. The growth and advection of this vorticity subsequently strongly affects the overall forces. To quickly predict and model the expected forces much work has gone into understanding this unsteady flow field and to develop low order models. Such models would ideally be able to compute the expected forces within a very short amount of time and a successful implementation of these would allow for gust rejection systems. Micro aerial vehicles, which are often compromised by high gust rations and turbulent fluctuations occurring in their flight envelopes could be one of the main benefactors.

Crucial to this endeavour is the correct prediction of where and when unsteady flow separation occurs as well as the strength of the shed vorticity. This talk will explore the unsteady development of the boundary layer vorticity of a rotating and surging cylinder through planar particle image velocimetry. Through this we seek to come closer to being able to predict the location of unsteady separation. The second objective of the talk is to explore the strength at which vorticity is shed. Once more, this is tackled by analysing the flow field around the circular cylinder. Special attention is payed to the boundary layer vorticity flux and the individual contributions to boundary layer vorticity.

This talk is part of the Fluids Group Seminar (CUED) series.

This talk is included in these lists:

• Acoustics Lab Seminars
• Engineering Department Acoustics/Combustion Student seminars
• Fluids Group Seminar (CUED)
• LR5, CUED.

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